The present invention relates to signal processing of a solid-state image-pickup device, and more particularly to a solid-state image-pickup device signal processing apparatus using a digital correlated double sampling circuit.
A conventional example related to a CCD of a television camera using a solid-state image-pickup device (hereinafter, described as CCD) in general and a correlated double sampling circuit is shown in FIG. 5 and FIG. 6.
In a block diagram of a solid-state image-pickup device signal processing apparatus of a conventional example shown in FIG. 5, a CCD 1 has a bias power source supplied at a bias power source input terminal 1a and a driving pulse supplied at a driving pulse input terminal 1b. And the CCD 1 is operated as publicly known by being supplied with a reset pulse and a read pulse generated by a timing signal generating circuit (hereinafter, described as TSG) 2.
In an output waveform diagram of a conventional solid-state image-pickup device shown in FIG. 6, as an analog output signal obtained by being photoelectrically converted and outputted by the CCD 1, an output signal is obtained in which three periods of a reset period tR, a field-through zero level period tF and a video signal period tS are repeated, as shown in the figure. Fluctuations of reset potentials contained in a field-through zero level period tF and a video signal period tS of said output signal correlate with each other.
In order to obtain the difference between these two sample values and remove the effect of reset noises, an output signal of the CCD is supplied to a correlated double sampling circuit 4 through an amplifier 3.
The amplified output signal of the CCD is inputted into a field-through S/H (sample hold) 4a and a video signal S/H 4b, and a field-through level signal sample-held during a field-through period at a specified timing by a field-through sample pulse outputted from TSG 2 is applied to the minus terminal of a differential amplifier 4c. 
On the other hand, a video signal sample-held during a video signal period tS in the video signal S/H 4b at a specified timing by a video signal sample pulse outputted from TSG 2 is applied to the plus terminal of the differential amplifier 4c, and the reset noises correlated with each other being contained in the respective signals are cancelled in output of the differential amplifier 4c and thereby an analog video signal in which reset noises have been removed is obtained in the output of the differential amplifier 4c. 
The video signal outputted from the differential amplifier 4c is made proper by an amplifier 5 and is supplied to an analog/digital (A/D) conversion circuit 6, and the A/D conversion circuit 6 converts this signal to a digital signal according to an A/D clock pulse from TSG 2.
The digital signal outputted from said A/D conversion circuit 6 is formed into a digital video signal according to a specified form by a digital signal processing circuit 7 operated with a DSP clock pulse outputted from TSG 2 and is outputted from an output terminal 8.    [Patent literature 1] Japanese Patent Laid-Open Publication No. 2000-13691
As shown in the conventional example, since an analog correlated double sampling circuit uses many analog circuits assembled with discrete components such as a field-through S/H circuit for sample-holding a field-through level tF period for each picture element, similarly a video signal S/H circuit for sample-holding a video signal tS period for each picture element, a differential amplifier and the like, miniaturization of it has been difficult.
And deterioration in accuracy of a signal level caused by occurrence of droop and the like due to inter-electrode capacitance and the like of semiconductor parts in an S/H circuit and circuit noises due to the complexity of a circuit configuration have not been able to be neglected.
Further, a digital correlated double sampling circuit using a correlated double sampling circuit and having a plurality of functions such as a flaw compensation, a shading compensation and the like specific to CCD added to it is provided.